Simpson Titen HD in holes drilled through bottom plate into concrete about 20 degrees off vertical?

[Engineerataltitude]

A builder drilled holes for 5/8" Simpson Titen-HD's to be retrofit into an existing concrete footing about 20 degrees off vertical because of some as-built constraints in the building. Off vertical to the outside, not length-wise to the sill. The building inspector caught this and said he had to get the EOR on the project to OK it or not. It is in a fairly lightly loaded exterio shear wall in a small light wood framed house, but in a high seismic zone in California.

I've not encountered this issue before.

Any ideas where I might get some guidance on the structural implications of this off-vertical sill anchor bolt installation?

 

[Lomarandil]

Certainly it can't be worse than an anchor embedded cos(20)=94% as long, with sin(20)=35% of the design tension load as additional shear, and located with edge distance based on where the anchor enters the concrete.

It doesn't happen to calc out as cleanly as that, does it?

 

[phamENG]

It's a proprietary product, so I would suggest reaching out to Simpson. If they won't back it, I wouldn't either.

 

[Engineerataltitude]

Tried Simpson already. They had no guidance on it.

There are about 55 holes drilled this way. Lots of labor to correct, so seemed worthwhile to try to find a resource to buy it as-is.

My gut feel is that it is OK. I just need to present an engineering rationale for that. Shear seem much more forgiving than tension for off-vertical as-built condition. Maybe looking at a reduction in shear value relative to the as-built vertical component as suggested would work.

Just seems like this must happen all the time somewhere. Surprising that there doesn't seem to be any technical/published guidance on the matter. I figured if there was, this group would know about it.

 

[phamENG]

What is your uplift load path? Are these taking tension? If so, tension at an angle to the axis will induce bending in the bolt. That alone might kill it. Did Simpson have any guidance on tolerances? Many of their screws are to be installed at a particular angle (they're fond of 22 degrees) but give a +/-. I haven't seen it for anchors, but maybe there's something in the installation literature?

It may be a lot of labor to correct, but that's the contractor's problem. If it really does work and you can prove it, I'm all for being a team player - but I won't take on the liability from the contractor just to make their life easier when they screw up.

 

[SWComposites]

What is the edge distance at the bottom of the holes to the footing edge? Is it greater than the minimum required for the fastener strength values in the datasheet?

 

[GeorgeTheCivilEngineer]

Is the extra labour to remove the obstruction to enable vertical installation? Would a different strengthening method be less labour intensive (maybe just putting in more skewed anchors)?

 

[Engineerataltitude]

Current angled holes meet all minimum edge and end distances for both sills and concrete. This is a retrofit of an old building to a foundation that had no anchorage to the concrete at all. Holes are drilled about 4 1/2" into the concrete (specs call for 4"min embedment)

Extra labor would be to drill new holes vertically through the bottom plate of the wall above, next to the floor rim joist and then through 18" of cripple wall. Would need a much longer drill and would need to do a lot more drywall repair in base of the wall above.

Of course, this all can be done, but I always like to look for solutions that save both time and money if I can. As long as it is defendable engineering-wise.

Actually if I can rationalize the skewed anchors being off by a percentage due to the skew, then if additional angled holes were drilled to make up for that deficit, that would certainly be a more cost-effective solution. Great idea! I could live with that.

 

[structSU10]

I would check with the reduced embedment due to the angle. the titen HD has a fixed length regardless of the hole length they drilled so use trig to figure out your new embedment depth vertically into the concrete. If this is a shear only anchor I don't think there is any other thing to consider. Just check the shear against the reduced embedment depth and if it works you are done.